I should've said "choose a secure line holding method that works for you, I use the middle finger grip".

The ability to hold the line with the rod hand is an important step for those deeply ingrained in holding the line with the other hand while single hand casting. I meant only to suggest a method, there are many to choose from. The important thing is that the line does not slip during the power stroke, whatever method you adopt. The ability to slip line out to optimal casting length is also important. The way you grip it specifically is not.